US Special Counsel Robert Mueller has found no evidence of collusion between President Donald Trump's election team and Russia in the 2016 election.
But he's left unresolved the question of whether Trump tried to obstruct justice by undermining investigations that have dogged his presidency.
Despite the inconclusive findings on obstruction US Attorney General William Barr said in a summary released on Sunday that Mueller had not found enough proof to warrant bringing obstruction charges against Trump.
It marked a political victory for Trump and he claimed "complete and total exoneration," although his Democratic opponents quickly expressed dissatisfaction and vowed to keep up their political assault against him.
The Kremlin said Russian President Vladimir Putin was now ready to improve ties with the United States but was up to Washington to make the first move.
Kremlin spokesman Dmitry Peskov repeated Moscow's denial of any interference in US elections and internal affairs or those of any other country.
Mueller's nearly two years of investigation ended with a finding that no one in Trump's campaign "conspired or coordinated with the Russian government," according to the four-page summary of Mueller's confidential report.
The long-awaited report into whether Trump's campaign colluded with Russia to help the Republican defeat his Democratic opponent, Hillary Clinton, marked a major milestone of his presidency as he prepares for his 2020 re-election battle.
Mueller did not reach a conclusion on whether Trump broke the law by interfering with the various probes into the 2016 election, but presented his evidence to Barr to make a determination.
Many of Trump's opponents had accused the president of obstructing the Russia probe when he fired former FBI Director James Comey in 2017.
"While this report does not conclude that the President committed a crime, it also does not exonerate him," Barr quoted Mueller as writing in the report that concluded his 22-month investigation, which has led to convictions of several of Trump's senior former aides.
Barr - a Trump appointee who took office last month - said he and Deputy Attorney General Rod Rosenstein concluded that the evidence did not justify bringing obstruction charges.
Democrats said they wanted to see Mueller's report for themselves as they launch congressional investigations of their own into the 2016 election and Trump's business and financial dealings.
US House of Representatives Speaker Nancy Pelosi and Senate Democratic leader Chuck Schumer said in a joint statement that the fact that Mueller had not cleared Trump on the obstruction issue "demonstrates how urgent it is that the full report and underlying documentation be made public without any further delay."
"It's a shame that our country had to go through this," Trump told reporters on Sunday.
"This was an illegal take-down that failed. And hopefully, somebody's going to be looking at the other side."
During his probe Mueller brought charges against 34 people, including Russian agents and former key allies of Trump.
